Necking machines have been used to form the neck on beer and beverage cans and the like for some time. These machines have evolved to the degree that reliable high speed precision necking is reliably realized. However, a drawback is encountered when switching from a run of one sized can to another, in that the downtime tends to be considerable. That is to say, the change-over requires the switching of an extensive number of elements and replacing them with new elements and/or re-adjusting current element to accommodate either the new diameter or length of the next can to be necked. Merely by way of example, with a change in diameter or neck profile, the current series of dies and knockout punches on each of the turrets needs to be changed. Transfer starwheels which temporarily hold, and then transfer cans to turret starwheels during their serpentine travel through the line or battery of necking turrets, need to be changed for a change in diameter and/or repositioned for a change in length, or both, if the can is both longer and different in diameter. The turret starwheels likewise must be changed with a change in diameter.
The close proximity of the turrets and the serpentine path along which the cans are conveyed, introduces problems such that, merely by way of example, when it is necessary to change over the dies, only two or three of these dies are accessibly exposed at the top of the turret on which they are supported, the remaining dies remaining between or below the turrets and thus totally inaccessible to an operator. This necessitates that an operator or operators, charged with the task of changing over these elements, change those which are exposed and rendered accessible, and then jog the machines to rotate the rotatable elements on each of the turrets to positions wherein the next two or three elements are rendered accessible. These dies are usually attached with a threaded collar and require a number of rotations to thread/unthread. This of course is inevitably carried out by hand.
In the event that twelve elements are carried per turret and there are 12-14 turrets involved in the necking process, no less than 168 operations are necessary. Thus, if it takes, for example, just 3 minutes on average to release one die and replace it with another and secure the new die in position, it will take at least 8 man hours to simply change over the dies on the aligned series of turrets. Accordingly, as will be understood, any change in change-over time is multiplied significantly.
Of course, this is merely the tip of the iceberg and, at least in addition to the above, it is necessary to replace/relocate (in the case of a change of diameter/length) the starwheels which respectively transport and position the cans for the sequence of necking operations necessary in order to achieve the required neck profile. It is also necessary to painstakingly set each of the can handling starwheels with respect to those on either side, so that can hand-off is carried out precisely and smoothly and without damage to cans.
Thus, to be able to reduce this non-productive labor intensive downtime, is highly desirable.